Recently the website I maintain has been growing a lot and I saw the point coming where I'd want to switch from apache to nginx, because I kept on reading that it performs way better.

Now I've done the switch, and I have to say, nginx is keeping up just fine. However, php-fpm is forming a problem. Where the php pages used to take 0.1 second to generate with the same load they now take around 3 seconds!

Furthermore the error.log from nginx is being spammed with errors like:

upstream timed out (110: Connection timed out) while connecting to upstream, client: ...

I also tried using unix sockets instead, but those would complain about the following:

connect() to unix:/tmp/php5-fpm.sock failed (11: Resource temporarily unavailable) while connecting to upstream

I've fiddled with settings here and there but nothing seems to work. Changing the amount of pm.max_children doesn't seem to help a lot either, but with it's current amount at 350 it seems to be the lesser of all evil.

The server that's being used has 3 GB RAM (not all of it is free due to a MySQL server also running) along with 2 dual-core processors (4 cores in total).

Am I doing something majorly wrong with the settings here, or is the server simply not capable enough?

EDIT: Here is the nginx server block

server {
    listen   80;
    listen   [::]:80 default ipv6only=on;
    root /var/www;
    index index.php index.html index.htm;

     server_name localhost;

    location / {
            try_files $uri $uri/ /index.html;
    }
    location /doc/ {
            alias /usr/share/doc/;
            autoindex on;
            allow 127.0.0.1;
            deny all;
    }
    location = /50x.html {
            root /usr/share/nginx/www;
    }

    location ~ \.php$ {
            fastcgi_split_path_info ^(.+\.php)(/.+)$;
            # NOTE: You should have "cgi.fix_pathinfo = 0;" in php.ini
            try_files $uri = 404;

            # With php5-cgi alone:
            fastcgi_pass 127.0.0.1:9000;
            # With php5-fpm:
            #fastcgi_pass unix:/tmp/php5-fpm.sock;
            fastcgi_index index.php;
            include fastcgi_params;
    }
    location ~ /\.ht {
            deny all;
    }
}

And the php-fpm pool:

[www]
user = www-data
group = www-data
listen = 127.0.0.1:9000
;listen = /tmp/php5-fpm.sock
listen.backlog = -1

pm = dynamic
pm.max_children = 350
pm.start_servers = 200
pm.min_spare_servers = 10
pm.max_spare_servers = 350
pm.max_requests = 1536

rlimit_files = 65536
rlimit_core = unlimited

chdir = /